The Vegamour products' results last as long as you continue using them. If you discontinue the use of hair serums, such as GRO Hair Serum or GRO+ Advanced Hair Serum, you will see your hair returning to its natural state within a few months since the growth cycle is longer.
For brow and lash serum, things will return to their natural state within a month since that's the length of a growth cycle. The serum works on your existing lashes and brows, and since all hair grows in cycles, once the hairs are naturally shed, you'll start to see your results fade.