sample.vue

<template>
 <b-table>
  <b-thead>
　　　　<b-tr>
　　　　　　<b-th class="text-left small text-muted border-top-0" style="width:15%;">名前</b-th>
   　  　　<b-th class="text-left small text-muted border-top-0" style="width:25%;" v-if="isRecordButton">メモ</b-th>
　　　　</b-tr>
  </b-thead>
  <b-tbody>
    <template v-for="(pattern, index) in patterns">
       <b-tr :key="pattern.id">
         <b-td>{{ pattern.name }}</b-td>
         <b-td>
           <button @click="openMemo">メモ記入</button>
             <memo-modal v-if="memoModalOpen">
              <div class="text-center">
                 <p>{{ pattern.name }}</p>
                 <p>メモ</p>
               </div>
               <div>
                 <b-form-textarea
                   id="`pattern_memo_${index}`" 
                   :name="`pattern_memo_${index}`" 
                   v-model="patterms[index].memo" >
                 </b-form-textarea>
               </div>
               <template slot="footer">
                  <b-button @click="closeMemo">閉じる</b-button>
               </template>
           </memo-modal>
         </b-td>         
       </b-tr>
  </b-tbody> 
</template>
<script>
/** MemoModalをインポート */
import MemoModal from '~/components/sample/MemoModal.vue'

export default {
　components: { 'memo-modal': MemoModal },
  data: () => {
    return {
       patterns: [
         {id: 1, name: test1, memo: ''},
         {id: 2, name: test2, memo: ''},
         {id: 3, name: test3, memo: ''},
       ],
       memoModalOpen: false
    }
  },
  methods: {
    openMemo() {
      this.memoModalOpen = true
    },
    closeMemo() {
      this.memoModalOpen = false
    }
  }
}
</script>

フォーマッター適用後のソース(<template v-for="(pattern, index) in patterns">の閉じタグが無いのでそれも追加)

<template>
  <b-table />
  <b-thead>
    <b-tr>
      <b-th class="text-left small text-muted border-top-0" style="width: 15%;">名前</b-th>
      <b-th class="text-left small text-muted border-top-0" style="width: 25%;" v-if="isRecordButton">メモ</b-th>
    </b-tr>
  </b-thead>
  <b-tbody>
    <template v-for="(pattern, index) in patterns">
      <b-tr :key="pattern.id">
        <b-td>{{ pattern.name }}</b-td>
        <b-td>
          <button @click="openMemo">メモ記入</button>
          <memo-modal v-if="memoModalOpen">
            <div class="text-center">
              <p>{{ pattern.name }}</p>
              <p>メモ</p>
            </div>
            <div>
              <b-form-textarea
                id="`pattern_memo_${index}`"
                :name="`pattern_memo_${index}`"
                v-model="patterms[index].memo"
              >
              </b-form-textarea>
            </div>
            <template slot="footer">
              <b-button @click="closeMemo">閉じる</b-button>
            </template>
          </memo-modal>
        </b-td>
      </b-tr>
    </template>
  </b-tbody>
</template>

<script>
/** MemoModalをインポート */
import MemoModal from '~/components/sample/MemoModal.vue'

export default {
  components: { 'memo-modal': MemoModal },
  data: () => {
    return {
      patterns: [
        { id: 1, name: test1, memo: '' },
        { id: 2, name: test2, memo: '' },
        { id: 3, name: test3, memo: '' },
      ],
      memoModalOpen: false,
    }
  },
  methods: {
    openMemo() {
      this.memoModalOpen = true
    },
    closeMemo() {
      this.memoModalOpen = false
    },
  },
}
</script>